Process for extracting precious metals



A c. P. PRIEST.' PPOCESS FOR- EXTRACTING PRECIOUS METALS.

APPLICMHQN FILED AuG.2|. |919. l 1,352,832. l A Pafentedsept.14,1920.-v

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PATENT oFFicE.

CHARLES P. PRIEST, OF PHILADELPHIA, PENNSYLVANIA.

PROCESS FOR EXTRACTING rILIREIJIGUS METALS.

To all whom t may concern:

Be it known that I, CHARLES. P. PRIEST, a citizen of the United States,residing at Philadelphia, in the county of Philadelphia and State ofPennsylvania, lhave invented certain new and useful Improvements 1nAProcesses for Extracting Precious Metals, of

mator or sluice partly by the electrolytic decomposition of waterpassing therethrough and partly by the action of the water on themetallic sodium formed by the electrolytic decomposition ofthe sodiumchlorid introduced with the slime The function of the hydrogen which is.of course in a nascent state, is to remove objectionable oxids andsulfurous coatings from the particles of precious metals to facilitatetheir amalgamay tion with the mercury.

An important object is the provision of a process which involvescontinually passing the slime and solutions over an amalga-` matedcopper plate forming one element of' an electrolyiing bath whereby theprocess will be continuous and rapid. i

It is possible t6 carry out the process with different varieties ofapparatus, though for purposes of illustration I have shown asatisfactory apparatus for the purpose in the accompanying drawing whichshows a somewhat diagrammatic elevation.y i

Inlcarrying out my process, the sand or ore is mixed with sodiumlchloridsolution and ground to the proper ineness, in some instances to as lineas 200 mesh. Solutions of hydrogen and mercury salt, such as mercurybichlorid, are then added to the slime and the whole is thoroughly`I'nixed and then 'l flowed through an electrolyzing sluice in which isprovided a copper plate amalgamated with mercury upon which theparticles of precious metal will be deposited.

In the drawing, the numeral lO designates Specification of LettersPatent. Patented Sept, 14, 1920, Application filed August 21, 1919.Serial No. 318,947. i

an ore grinder of conventional type driven by suitable means andhavingan inlet end' ll into which the ore or sand is fed and'into which issuppliedkthe sodium chlorid or common salt solution. Disposed inposition to receive the ground material discharged from the grinder l0is a mixing device l2 of any ordinary construction and of either thehorizontal or vertical type. whrereby the slime or pulp from the grinderenters the mixer there is introduced by any At the point 13 suitablemeans, a solution of mercury bichlorid and a water solution of hydrogen.The purpose of introducing the hydrogen, which is in the molecularstate, is to saturate the slime or pulp with hydrogen for a purpose tobe described. The slime or pulp, after being thoroughly mixed with thesolution in the mixer 12, is'discharged into the sluice 14 ywithin whichis disposed a plurality of lswinging anode plates l5 connected in anelectric circuit with a suitable cathode plate 16.

In carrying out the process the sodiumv chlorid in solution is broken upint-o its con*` stituents, metallic sodium and chlorin, which being inthe nascent state, are highlyactive. The chlorin acts as a cleansingagent and assists in removing objectionable coatings from thev particlesofprecious metal. The mercury bichlorid is broken up into metallicmercury and chlorin and the metallic mercury is of course deposited uponthe plates. The nascent metallic sodium formed by the breaking up of thesalt solution unites with the metallic mercury to form mercury andsodium amalgam which has a great affinity for the precious metals.vThemet'allic sodium furthermore is acted upon bythe water of thesolution and forms sodium hydroxid and hydrogen gas. Sodium hydroxid isa cleansing agent and will therefore act ad-.

vantageously upon the particles of precious metals. The hydrogenliberated isin a nascent state and consequently highly active and willgo to the mercury and sodium amalgam and greatly increase the activitythereof so that as the particles of precious metal passing through thesluice come in contact with the plates they will be deposited thercon/and amalgamate therewith. It might .also be stated that some of thehydrogen will assist in removing oXids from the precious metals and makethem clean and bright to facilitate their amalgamation.

L The preliminary saturation of the solution with hydrogen prevents thehydrogen liberated from being absorbed.

The combined use of the three powerful amalgamating agents, mercury,sodium and*` hydrogen forms a perfect amalgam which is soft,..smooth,elastic, tenacious, yet plastic and which willnot crumble. Thehydrogensodium-mercury amalgam is chemicallypure and has such anaffinity for precious metals that the particles of the latter will beattracted even under the most adverse conditions, such as'the presenceof silicious, arsenical, greasy, sulfurous or rusty coatings.

I claim 1. A process of extracting precious metals from ores or sandsconsisting in grinding the ores or sands in a solution of a sodiumcompound, then mixing with a hydrogen solution and a mercury compoundsolution, and then electrolyzing the slime whereby to effeetamalgamation.

2. A process for the extraction and recovery of precious metals fromores `or sands consisting in grinding the ores or sands in a solutlon ofsodium chlorid, then adding .hydrogen and a solution of mercurybichlorid, and subsequently effecting amalgamation by electrolysis.

In testimony whereof I hereto affix my signature.

CHARLES P. PRIEST. l

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